The present invention relates to the formation of microparticles of water soluble cellulose acetate and water soluble derivatives of cellulose acetate.
Microparticles of cellulose organic esters generally and microparticles of cellulose acetate particularly are known in the art. Such particles are used for immobilization of enzymes, filter packings, chromatographic packings and the controlled release of chemicals. Various methods of forming cellulose organic ester particles are known in the art. For example, U.S. Pat. Nos. 4,390,691 and 4,461,892 to Nishikawa et al disclose processes for preparing porous spherical cellulose particles which include suspending a cellulose ester solution dissolved in a chlorinated hydrocarbon solvent into an aqueous solution, evaporating the solvent to form spherical particles and saponifying the spherical particles. However, these microparticles are not soluble in water thus the uses thereof are somewhat restricted especially with respect to the controlled release of chemicals and as catalyst carriers.
Water soluble cellulose acetate films and fibers and processes for producing them are known in the art. U.S. Pat. No. 2,129,052 to Fordyce, U.S. Pat. No. 2,448,082 to Creamer, U.S. Pat. No. 3,482,011 to Bohrer and U.K. Patent No. 696,903 to Davoud all disclose that water soluble and water susceptible cellulose acetate film and fibers can be produced by utilizing various esterification and/or hydrolysis techniques on cellulose acetate which is normally insoluble in water. Additionally, Russian Patent No. 1740744 discloses using water soluble cellulose acetate as a tablet binder for use by the pharmaceutical industry. However, there is no disclosure of the formation of water soluble cellulose acetate microspheres.